Question: If $2a + 9b = -8$ and $8x + 6y = -4$, what is $-64x - 16a - 48y - 72b$ ?
Explanation: $= -16a - 72b - 64x - 48y$ $= (-8) \cdot (2a + 9b) + (-8) \cdot (8x + 6y)$ $= (-8) \cdot (-8) + (-8) \cdot (-4)$ $= 64 + 32$ $= 96$